1. Field of the Invention
The present invention pertains to a system for deriving useful heat energy from the solar radiation transmitted through window and door openings in buildings and other structures. Said openings have at least partially transparent glazing comprised of glass, plastic or other transmissive material.
Buildings and other structures having windows and doors directly exposed to sunlight create a problem for the occupants because the solar radiant energy entering through said windows and doors provides harsh lighting and radiant heating of objects within the building. Such lighting conditions have been proven to be not conducive to a desirable level of productivity of workers and students exposed thereto. Moreover, radiant heating of furniture, carpeting and other objects by direct solar radiation is not desirable as such exposure is destructive to various man-made and natural textiles and dyestuffs.
However, current economic conditions dictate that rather than simply reflecting the undesired light back through the windows and doors of a building exposed to direct sunlight, it is economically preferable to capture said radiant energy as it enters the building and convert it into useful thermal energy for the purpose of heating the interior of the structure.
Therefore, it is desirable to provide a system for collecting solar energy entering a building through its windows and doors and converting the solar energy to thermal energy for the purpose of space heating without exposing the interior occupants or contents to direct exposure of harsh and intense solar radiation. Moreover, it is desirable to provide means for selectively controlling the amount of radiation entering the room to affect a proper balance between available heat and light. It is also desirable to provide such a system for existing buildings and other structures without substantially modifying existing glazing or blinds.
2. Description of the Prior Art
One prior system for using solar energy for space heating is disclosed in U.S. Pat. No. 4,090,497 to Kelly. In this system, solar radiation strikes the parallel transparent sides of a closed chamber which contains a heat exchanger for transmitting heat converted from solar energy by radiation absorbing means such as the louvers of venetian blinds and the like.
The disadvantage of this type of system is that a complex mechanical arrangement must be provided for adjusting the angle of the louvers to maximally capture radiant solar energy. Moreover, an expensive chamber must be provided for the system to operate properly.
U.S. Pat. No. 4,459,975 to Hobart discloses a solar energy converter for use in a location adjacent to the inside of a window to receive solar energy and change it to useful heat. This invention utilizes curved adjustable blinds for the purpose of converting radiant energy into heat energy. Disadvantageously, the Hobart disclosure does not provide a means for excluding both heat and light. Consequently, if one were to close the blinds to exclude light transmitted into the structure, a concomitant rise in heat transmitted to the interior of the structure would occur. Likewise, adjusting the blinds to maximally admit light to the interior of the building would result in minimum heat conversion. There are no means for reducing both heat and light.
U.S. Pat. No. 4,379,449 to Wiggins et al. discloses a solar hot-air system consisting primarily of a glass, a screen, a collector and air chambers as well as two sheets of aluminum to trap and hold heat. Also included is an electric fan to extract heat from the collector while the sun is shining. This unit is not intended to be installed in a window or door or other opening in a structure where it is desirable to at least partially utilize solar radiation for lighting purposes.